The Framingham Study

Please note that this section contains my personal notes from my readings on this topic.

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After World War II, the National Heart Institute was created with a modest budget and a difficult mission. Scientists knew that the greasy plagues that lined the arteries of diseased hearts were composed of cholesterol, phospholipids and fatty acids, but they didn’t know why these lesions developed, how they developed or exactly how they led to heart attacks. In the search for answers, the National Heart Institute decided to follow a population over several years, to keep detailed medical records of everybody in the population and to see who got heart disease and who didn’t. The scientists headed to Framingham, Massachusetts.

Located just outside of Boston, Framingham is steeped in American history… In 1948, the town assumed its most famous role. Over 5,000 residents of Framingham, both male and female, agreed to be poked and prodded by scientists over the years so that we might learn something about heart disease.

And learn something we did. By watching who got heart disease and who didn’t, and comparing their medical records, the Framingham Heart Study developed the concept of risk factors such as cholesterol, blood pressure, physical activity, cigarette smoking and obesity. Because of the Framingham Study, we now know that these risk factors play a prominent role in the causation of heart disease. Doctors have for years used a Framingham prediction model to tell who is at high risk for heart disease and who is not. Over 1,000 scientific papers have been published from this study, and the study continues to this day, having now studied four generations of Framingham residents.

The shining jewel of the Framingham Study is its findings on blood cholesterol. In 1961, they convincingly showed a strong correlation between high blood cholesterol and heart disease. Researchers noted that men with cholesterol levels “over 244 mg/dL (milligrams per deciliter) have more than three times the incidence of CHD (coronary heart disease) as do those with cholesterol levels less than 210 mg/dL. The contentious question of whether blood cholesterol levels could predict heart disease was laid to rest. Cholesterol levels do make a difference. In this same paper, high blood pressure was also demonstrated to be an important risk factor for heart disease.

… Researchers wrote, “… it appears that a preventive program is clearly necessary.” Simply lower the risk factors, such as blood cholesterol and blood pressure, and you lower the risk of heart disease.

In modern-day America cholesterol and blood pressure are household terms. We spend over 30 billion dollars a year on drugs to control these risk factors and other aspects of cardiovascular disease. Almost everyone now knows that he or she can work to prevent a heart attack by keeping his or her risk factors at the right levels. This awareness is only about 50 years old and due in large measure to the scientists and subjects of the Framingham Heart Study.

When the Framingham Heart Study was just beginning, there were already doctors who were trying to figure out how to treat heart disease, rather than just prevent it. In many ways, these investigators were ahead of their time because their interventions, which were the most innovative, successful treatment programs at the time, utilized the least advanced technology available: the knife and fork.

These doctors noticed the ongoing research at the time and made some common-sense connections. They realized that:

excess fat and cholesterol consumption caused atherosclerosis (the hardening of the arteries and the accumulation of plaque) in experimental animals

eating cholesterol in food caused a rise in cholesterol in the blood

high blood cholesterol might predict and/or cause heart disease

most of the world’s population didn’t have heart disease, and these heart disease-free cultures had radically different dietary patterns, consuming less fat and cholesterol

So they decided to try to alter heart disease in their patients by having them eat less fat and cholesterol.

One of the most progressive doctors was Dr. Lester Morrison of Los Angeles. He started a study in 1946 (two years before the Framingham Study) to determine the relationship of dietary fat intake to the incidence of atherosclerosis. In his study he instructed fifty heart attack survivors to maintain their normal diet and fifty different heart attach survivors to consume an experimental diet.

In the experimental diet group he reduced the consumption of fat and cholesterol. One of his published sample menus allowed the patient to have only a small amount of meat two times a day: two ounces of “cold roast lamb, lean, with mint jelly” for lunch, and another two ounces of “lean meats” for dinner. Even if you loved cold roast lamb with mint jelly, you weren’t allowed to eat much of it. In fact, the list of prohibited foods in the experimental diet was fairly long and included cream soups, pork, fat meats, animal fats, whole milk, cream, butter, egg yolks and breads and desserts made with butter, whole eggs and whole milk.

Did this progressive diet accomplish anything? After eighty years only 12 of 50 people eating their normal American diet were alive (24%). In the diet group, 28 people were still alive (56%), almost 2.5 times the amount of survivors in the control group.

After 12 years, every single patient in the control group was dead. In the diet group, however, 19 people were still alive, a survival rate of 38%. While it was unfortunate that so many people in the dietary group still died, it was clear that they were staving off the disease by eating moderately less animal foods and moderately more plant foods.

In 1946, when this study began, most scientists believed that heart disease was an inevitable part of agin, and nothing much could be done about it. While Morrison didn’t cure heart disease, he proved that something as simple as diet could significantly alter its course, even when the disease is so advanced that it has already caused a heart attack.

Another research group proved much the same thing at about that time. A group of doctors in Northern California took a larger group of patients with advanced heart disease and put them on a low-fat, low-cholesterol diet. These doctors found that the patients who ate the low-fat, low-cholesterol diet died at a rate four times lower than patients who didn’t follow the diet.

It was now clear that there was hope. Heart disease wasn’t the inevitable result of old age, and even when a person had advanced disease, a low-fat, low-cholesterol diet could significantly prolong his or her life. This was a remarkable advance in our understanding of the number one killer in America. Furthermore, this new understanding made diet and other environmental factors the centerpieces of heart disease.